缘起
最近阅读<<Go微服务实战>> (刘金亮, 2021.1)
本系列笔记拟采用golang练习之
案例需求(聊天服务器)
- 用户可以连接到服务器。
- 用户可以设定自己的用户名。
- 用户可以向服务器发送消息，同时服务器也会向其他用户广播该消息。
目标(Day 3)
- 在Day 2中, 已基本完成功能性编码, 测试也通过了, 今天尝试压测, 并诊断是否存在内存和routine泄漏
过程
- 修改单元测试代码, 并发客户端增加到50个, 每个客户端随机1-3秒发送一条消息
- 添加ILoggingService, 以更方便的采集全局日志
- 使用pprof包的api, 采集heap和goroutine的诊断日志
- 使用go tool pprof <诊断日志>, 观察是否存在内存和routine泄漏
- 发现单元测试总是failed, 总有若干tChatClient, 服务端未打印关闭日志
- 查看routine诊断日志, 发现存在routine泄漏
- 在tChatClient中添加更详细的函数调用日志, 发现是closeChan通道写入阻塞导致
- 修复routine泄漏的bug, 加大并发客户端到500个, 并进行多轮测试, 观察是否存在内存和routine泄漏
单元测试
- ChatServer_test.go
- 增大客户端并发数, 并添加pprof诊断
- 诊断ILoggingService.AllLogs(), 判断所有客户端是否完成连接/断开的闭环
package chat_server
import (
"fmt"
cs "learning/gooop/chat_server"
"math/rand"
"os"
"runtime"
"runtime/pprof"
"strings"
"sync"
"testing"
"time"
)
func Test_ChatServer(t *testing.T) {
fnAssertTrue := func(b bool, msg string) {
if !b {
t.Fatal(msg)
}
}
// create dump file
memProfile, err := os.Create("/home/ioly/chat_server_mem.profile")
if err != nil {
t.Fatal(err)
}
cpuProfile, err := os.Create("/home/ioly/chat_server_cpu.profile")
if err != nil {
t.Fatal(err)
}
rtnProfile, err := os.Create("/home/ioly/chat_server_routine.profile")
if err != nil {
t.Fatal(err)
}
err = pprof.StartCPUProfile(cpuProfile)
if err != nil {
t.Fatal(err)
}
defer pprof.StopCPUProfile()
port := 3333
server := cs.NewChatServer()
err = server.Open(port)
if err != nil {
t.Fatal(err)
}
clientCount := 500
wg := &sync.WaitGroup{}
rnd := rand.New(rand.NewSource(time.Now().UnixNano()))
address := fmt.Sprintf("localhost:%v", port)
for i := 0;i < clientCount;i++ {
err, client := cs.DialChatClient(address)
if err != nil {
t.Fatal(err)
}
id := fmt.Sprintf("c%02d", i)
//client.RecvHandler(func(client cs.IChatClient, msg cs.IMsg) {
// t.Logf("%v recv: %v\n", id, msg)
//})
wg.Add(1)
go func() {
client.SetName(id)
client.Send(&cs.NameMsg{id })
n := 0
duration := rnd.Intn(3) + 1
for range time.Tick(time.Duration(duration) * time.Second) {
client.Send(&cs.ChatMsg{id, fmt.Sprintf("msg %02d from %v", n, id) })
n++
if n > 10 {
break
}
}
client.Close()
wg.Done()
}()
}
// wait and set status
done := []bool{false}
go func() {
wg.Wait()
done[0] = true
}()
// print passed seconds
passedSeconds := 0
for range time.Tick(time.Second) {
passedSeconds++
t.Logf("%v seconds passed", passedSeconds)
if done[0] {
break
}
}
time.Sleep(5*time.Second)
server.Close()
// dump heap file
runtime.GC()
err = pprof.Lookup("heap").WriteTo(memProfile, 0)
if err != nil {
t.Fatal(err)
}
err = pprof.Lookup("goroutine").WriteTo(rtnProfile, 0)
if err != nil {
t.Fatal(err)
}
// check server logs
logs := cs.Logging.AllLogs()
fnHasLog := func(log string) bool {
for _,it := range logs {
if strings.Contains(it, log) {
return true
}
}
return false
}
for i := 0;i < clientCount;i++ {
msg := fmt.Sprintf("tChatClient.postConnClosed, c%02d, serverFlag=false", i)
fnAssertTrue(fnHasLog(msg), "expecting log: " + msg)
msg = fmt.Sprintf("tChatServer.handleIncomingConn, clientCount=%v", i + 1)
fnAssertTrue(fnHasLog(msg), "expecting log: " + msg)
msg = fmt.Sprintf("tChatClient.postConnClosed, c%02d, serverFlag=true", i)
fnAssertTrue(fnHasLog(msg), "expecting log: " + msg)
msg = fmt.Sprintf("tChatServer.handleClientClosed, c%02d", i)
fnAssertTrue(fnHasLog(msg), "expecting log: " + msg)
}
}
测试输出
并发500, 仅末尾部分
tChatClient.beginWrite, write error, c496, serverFlag=true
tChatClient.beginWrite, <- closeChan, c496, serverFlag=true
tChatClient.postConnClosed, c496, serverFlag=true
tChatServer.handleClientClosed, c496
tChatServer.handleClientClosed, c496, clientCount=1
tChatClient.closeConn, c498, serverFlag=false
tChatClient.beginWrite, <- closeChan, c498, serverFlag=false
tChatClient.beginRead, read error, c498, serverFlag=false
tChatClient.postConnClosed, c498, serverFlag=false
tChatClient.beginRead, read error, c498, serverFlag=true
tChatClient.closeConn, c498, serverFlag=true
tChatClient.beginWrite, <- closeChan, c498, serverFlag=true
tChatClient.postConnClosed, c498, serverFlag=true
tChatServer.handleClientClosed, c498
tChatServer.handleClientClosed, c498, clientCount=0
ChatServer_test.go:97: 34 seconds passed
--- PASS: Test_ChatServer (39.50s)
PASS
ok command-line-arguments 39.535s
routine泄漏诊断(修复前)
有泄漏时的诊断日志(并发50)
$ go tool pprof ~/chat_server_routine.profile
File: chat_server.test
Type: goroutine
Time: Mar 9, 2021 at 9:12am (CST)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) top
Showing nodes accounting for 4, 100% of 4 total
Showing top 10 nodes out of 21
flat flat% sum% cum cum%
3 75.00% 75.00% 3 75.00% runtime.gopark
1 25.00% 100% 1 25.00% runtime/pprof.runtime_goroutineProfileWithLabels
0 0% 100% 1 25.00% command-line-arguments.Test_ChatServer
0 0% 100% 1 25.00% learning/gooop/chat_server.(*tChatClient).beginWrite
0 0% 100% 1 25.00% learning/gooop/chat_server.(*tChatClient).closeConn
0 0% 100% 1 25.00% main.main
0 0% 100% 1 25.00% runtime.chanrecv
0 0% 100% 1 25.00% runtime.chanrecv1
0 0% 100% 1 25.00% runtime.chansend
0 0% 100% 1 25.00% runtime.chansend1
(pprof)
可以看到closeConn函数阻塞
func (me *tChatClient) closeConn() {
if !atomic.CompareAndSwapInt32(&me.closeFlag, 0, 1) {
return
}
Logging.Logf("tChatClient.closeConn, %v, serverFlag=%v", me.name, me.serverFlag)
me.closeChan <- true
}
从代码看, closeConn函数阻塞只有一种可能, 就是closeChan阻塞.
这个原因有点诡异, 因为已经加了atomic.CompareAndSwapInt32保护,
仍然导致阻塞, 唯一原因是并发环境下, closeChan尚未开始读取, 是无法写入的.
修复routine泄漏
就是给导致写阻塞的closeChan加上缓冲, 大小等于closeConn函数的可能调用入口数量
func openChatClient(conn net.Conn, serverFlag bool) IChatClient {
it := &tChatClient{
conn: conn,
openFlag: 0,
closeFlag: 0,
serverFlag: serverFlag,
closeChan: make(chan bool, 3), // 给closeChan添加缓冲区!!
sendChan: make(chan IMsg, gMaxPendingSend),
name: "anonymous",
sendLogs: []IMsg{},
dropLogs: []IMsg{},
recvLogs: []IMsg{},
}
it.open()
return it
}
routine泄漏诊断(修复后)
修复后, 加大并发到500, 未发现明显routine泄漏(不存在业务代码导致挂起的routine)
$ go tool pprof ~/chat_server_routine.profile
File: chat_server.test
Type: goroutine
Time: Mar 9, 2021 at 9:28am (CST)
Entering interactive mode (type "help" for commands, "o" for options)
(pprof) top
Showing nodes accounting for 3, 100% of 3 total
Showing top 10 nodes out of 17
flat flat% sum% cum cum%
2 66.67% 66.67% 2 66.67% runtime.gopark
1 33.33% 100% 1 33.33% runtime/pprof.runtime_goroutineProfileWithLabels
0 0% 100% 1 33.33% command-line-arguments.Test_ChatServer
0 0% 100% 1 33.33% main.main
0 0% 100% 1 33.33% runtime.chanrecv
0 0% 100% 1 33.33% runtime.chanrecv1
0 0% 100% 1 33.33% runtime.main
0 0% 100% 1 33.33% runtime/pprof.(*Profile).WriteTo
0 0% 100% 1 33.33% runtime/pprof.profileWriter
0 0% 100% 1 33.33% runtime/pprof.writeGoroutine
(pprof)
(未完待续)
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